Long chain amine oxide surfactants produce rich stable foams in water and have properties that result in a high degree of grease cutting. Therefore, amine oxide surfactants are frequently chosen as a component of hand dishwashing liquids, cleansers, and other products where foaming is desirable. Amine oxides are also capable of being successfully used in chlorine/bleach products where other surfactants may not be acceptable.
Long chain amine oxide surfactants may be prepared by the oxidation of tertiary amines. Long chain amine oxides may be produced in a process comprising oxidizing a tertiary amine with hydrogen peroxide. In such reactions, hydrogen peroxide in added to the process in a stoichiometric excess to ensure that predominantly all the tertiary amine is converted to amine oxide. The oxidation reaction is typically conducted at a temperature in the range of from about 60° to about 100° C. After conversion of the tertiary amine to amine oxide, there remains excess hydrogen peroxide in the process stream containing the amine oxide. The presence of even relatively small amounts of excess hydrogen peroxide (i.e. in excess of 100 ppm) in amine oxides used in formulation of liquid detergents can result in skin irritation and odor problems. The odor problems are especially evident in liquid detergents that are formulated with diamine compounds such as diaminopentane, a pH buffer that may be used in detergents.
Conventional processes rely on simple decomposition of the excess hydrogen peroxide to eliminate the hydrogen peroxide from the product stream. The decomposition is achieved by maintaining the product stream comprising the amine oxide at high temperatures for a sufficient time. Unfortunately, high temperature thermal decomposition of the hydrogen peroxide results in formation of unwanted byproducts in the amine oxide surfactant. In certain applications, if the high temperature hydrogen peroxide decomposition is continued to a point where the hydrogen peroxide is totally removed from the amine oxide surfactant, other concerns such as color stability and other odor problems may occur.
Therefore, there is a need for a process to more efficiently remove the hydrogen peroxide from a product process stream comprising long chain amine oxides. More specifically, there is a need for a process that can decompose the hydrogen peroxide from a process stream comprising long chain amine oxides to a concentration of less than 100 ppm, as well as reducing the formation of byproducts formed by excess heating of the process stream.